Public rest rooms debuted in the late 19th-century to address sanitation concerns created by a growing population and limited availability of private toilets, according to the American Restroom Association. As the infrastructure aged, however, the cost of maintaining public toilets increased, and more illicit and illegal activities took place in public rest rooms, resulting in safety concerns. Eventually, many public toilets closed, leaving people without access to rest rooms when away from home.
The Occupational Safety and Health Administration specifies the number of toilets required in U.S. workplaces based on the number of employees. The American Restroom Association reports that most public toilet regulations in the United States come from zoning and building codes at the state or local level. For example, several states use square footage to determine the number of toilets required for covered malls. Some states, such as New York and Oregon, use occupancy capacity to specify minimum toilet requirements for restaurants.
As of 2010, several U.S. organisations have proposed ways to keep public toilets safe, including the American Restroom Association and Public Hygiene Lets Us Stay Human (PHLUSH). Both groups recommend well-maintained interior and exterior lighting, regular monitoring, vandalism-resistant paint and secured fixtures.
The American Restroom Association notes that most existing public toilet regulations define "gender parity" as an equal number of facilities for men and women. The group cites numerous medical studies that found that women need to use the rest room more often than men, however, particularly pregnant women. Advocates for public toilets encourage redefining gender parity as two toilets for women for every one urinal for men.